Like rygh, I use IO regular and I used it on my last tank in Texas as well. It's cheap, easy, and I works fine. For me, it mixes up to Ca = 430 - 450 ppm, dKH = 8 - 9. My new system hasn't had much growth yet, but I had good growth of sps and a clam in my system in Texas. If you have a big calcium demand, you'll end up dosing Ca and alk in some way between water changes anyway, so you might as well use a cheap salt. Besides, I read some posts on reefcentral from people who run public aquaria and they said that most public aquaria either use regular IO or make their own salt mixes (like the Steinhart aquarium does). Point is the regular IO works fine.